Connecting rod mounting



June 26, 1934. E, M, TUCKER 1,964,096

CONNECTING non MOUNTING Filed Nov. 21. 1931 EM QLCI: er

BYQ Surg'.-

TTTTTT EY Patented .lune 26, 1934 YUNITED STATES PATENT OFFICE .2 laims.

"This invention relates 'to 'internal .Combustion engines of the 4cycle type and particularly to the bearing or mounting arrangement between the crank .pin of the crank shaft and the adja- 5 cent end of the connecting rod. The .fliciency and power of a gas engine depend to a large extent on the thorough .scavenging of the burnt gases and on the subsequent drawing in of a sufficient quantity of explosive mixture to provide for the necessary power impulse being given to the piston. As engines are now built the movement of the piston is the same on all strokes. .If the piston .is retracted in the cylinder during the exhaust stroke so as .to expel practically all the burnt gases, it then approaches .the cylinder head so closely on the compression stroke as to compress the fresh charge to an impracticable degree, and a relatively small charge must be taken in to avoid this contingency. Ii, on the other hand, the clearance between the piston and cylinder head at the end of the compression stroke is suiciently great to give the proper compression, the piston will not approach the cylinder head suiciently on the exhaust stroke to effectively expel all the burnt gases. It has therefore been necessary to choose a middle path for the piston movement, preventing the fullest possible efficiency of the engine being obtained.

It is the principal object of myinvention to eliminate the above defective features by so mounting the connecting rod on the crank pin that the piston will be moved very close to the cylinder head on the exhaust stroke but will not approach so close on the compression stroke. Practically all burnt gases are therefore expelled leaving the cylinder in a thoroughly scavenged condition and a relatively large charge of fresh mixture is then taken in which will not be diluted or contaminated with any burnt gases. Also said fresh charge is then compressed to the necessary extent to enable the engine to operate at high efciency. As a result of this arrangement the emciency or power development of an engine may be increased from 25% to 40% or thereabouts depending on the particular design of the engine.

It will also eliminate the need of the low speed jet in the carbureter, and will permit of a lower idling speed being maintained due to the absence 0 of burnt gases in the cylinders. The heat will likewise be reduced and the lubrication improved by reason of the more complete scavenging of the cylinders.

A further object of the invention is to produce a simple and inexpensive device and yet one which (GI. 12B- 78) will be exceedingly effective for .the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following speciiication and claims.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Fig. l isa side elevation of a crank showing my connecting rod mounting arrangement.

Fig. 2 is an end view of the same showing the adjacent `crank arm removed.

Fig. 3 is Va :transverse section on the line 3-3 oi" Fig. V2.

Referring now more particularly to the char- A'I0 acters of reference on the drawing, the numeral l denotes a crank shaft having spaced crank arms 2 connected by a crank pin -3 as usual. In the present instance the structure is shown as being of that type such as is used in radial or airplane engines in which the pin at one end is removably mounted in the arm so that the connecting rod bushing may be slid on from one end of the pin and need not `be split.

When a one-piece crank shaft is used, the rod bushing and rod-end must of course be split in order to assemble them on the crank pin.

Turnably mounted on the pin is an eccentric bushing 4 which is engaged by the adjacent end of the connecting rod 5 in turning relation. A 85 spur gear 6 is xed on one end of the crank pin 3, between the eccentric bushing 4 and the adjacent crank arm 2. This gear meshes with a pinion '7 fixed on a shaft 8 journaled in and extending through the bushing. On its opposite end, the shaft 8 carries a pinion 9 which meshes with an internal gear l0 xed on the adjacent end of the connecting rod 5 concentric with the bushing. The ratio of the pinions to the gears is such that the eccentric makes one full revolution with each .two full turns of the crank shaft, such rotation being of course imparted to the bushing by the pinion unit which engages the rotating pin gear and the relatively stationary connecting rod gear.

It will therefore be seen that with the rotation of the crank shaft the eccentric bushing will be rotated on the crank pin and will constantly alter its position relative thereto. The ratio of the gears and pinions is such that the bushing 105 will be given one complete rotation about the crank pin with every two full revolutions of the crank shaft, or once for every 4-cycle movement of said shaft. When assemblying the parts the bushing is located on the pin so as to occupy its 11'0 lowest position relative to the pin when the crank is at top dead center position at the end of the compression stroke and the piston 1l is correspondingly at its topmost position in the cylinder 12 as in the third gure of the diagram. The piston will then be further from the head of the cylinder than if the connecting rod engaged the crank pin as usual, as Will be evident, and a greater space is had for the fresh charge of fuel mixture. There is also an increase in intake suction due to the absence of burnt gases in the combustion chamber, and a larger and purer charge of fresh mixture will be drawn into the cylinder.

Similarly at the termination of the exhaust stroke as in the first figure of the diagram the bushing will then be at its topmost position relative to the crank pin and the piston will be closer to the head of the cylinder than is ordinarily the case. Practically all burnt gases will therefore be expelled. When the crank is at its lowest dead center position at the termination of the intake and firing strokes the vbushing will be half way between its uppermost and lowermost positions and the connecting rod will therefore be offset to the right or left of the axis of the crank pin. On the firing stroke this is of course of advantage since the distance between the axis of the crank shaft and that of the connecting rod is greater than the distance between the axes of the crank shaft and pin and the leverage on the crank shaft is relatively great with no actual increase in the length of the stroke. This is assuming that the crankshaft in the drawing is turning in a counterclockwise direction.

A different arrangement but one which will give the same result is shown in Figs. 4 to 6. In this case a spur gear 13 is fixed on one end of the crank pin 3a, between the eccentric bushing 4a. and the adjacent crank arm 2a. This gear meshes with a pinion 14 xed on a shaft l5 journaled in and extending through the bushing. On its opposite end the shaft l5 carries a pinion 16 fixed thereon which meshes with an internal gear 17 xed on the adjacent end of the connecting rod 5a concentric with the bushing. In this structure the ratio of the pinions to the gears is such that the eccentric makes one full revolution with each two full turns of the crank shaft, such rotation being of course imparted to the bushing by the pinion unit which engages the rotating pin gear and the relatively stationary connecting rod gear.

In both cases, the relative speed between the contacting surfaces of the bushing and crank pin, and of the bushing and connecting rod, is reduced 50% from the speed had when the rod engages the crank pin direct. This is because the bushing itself is turning in the connecting rod, at only half crank shaft speed. As a result the frictional heat due to such rotation is lessened, and lubrication oi the bearing surfaces is rendered easier and more eiective. This feature alone therefore is of great benefit and is considered one of the important objects of the invention.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as dened by the appended claims.

Having thus described my invention what I claim as new and useful and desire to secure by Letters Patent is:

1.1n combination, a crank shaft having a crank pin, an eccentric bushing thereon, a connecting rod engaging said bushing, a gear fixed with the pin, an internal gear on the connecting rod concentric with the bushing and free of the pin gear, and gearing connections between said gears to cause the bushing to rotate one full turn about the pin with every two full turns of the shaft.

2. In combination, a crank shaft having a crank pin, an eccentric bushing thereon, a connecting rod engaging said bushing, a gear fixed on and concentric with the pin beyond one end of the bushing, an internal gear on the connecting rod beyond the opposite end of the bushing and concentric therewith, a pinion turnably mounted 'in the bushing and engaging the pin gear, and another pinion mounted in xed axial connection with the first pinion and engaging the rod gear.

EMMITT M. TUCKER. 

